Channel coding with multilevel/phase signals
IEEE Transactions on Information Theory
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The special bandwidth efficiency features of coded single carrier multilevel data communication signals pave the way for implementation of high speed data transmission via public analogue telephone networks. The minimum distance of nonredundant coded signals and the minimum free-distance of redundant coded signals are discussed and their influence on error rates is analysed. Security of data on public networks, where it is subject to noise and interference, is improved by advanced trellis coding. Combining the trellis with multilevel signalling provides high speed data modems with security against nearly all spurious signals, transient noise and circuit impairments. The signal structure and coding algorithm of CCITT's recent recommendations on 9600 bit/s and 14 400 bit/s modems for PSTN and leased lines are also discussed.